INTRONN INC.

21st September 2007

Proteome Sciences plc (“Proteome Sciences”) today announces that VIRxSYS Corporation has acquired the core technology and assets of Intronn Inc. (a company in which Proteome Sciences retains a 43 percent shareholding) in exchange for the issuance of preference stock in VIRxSYS.

VIRxSYS is a private US biotechnology company founded in 1998 developing gene therapies for HIV and genetic disorders using a lentiviral vector delivery platform. VIRxSYS’s initial focus was directed towards HIV and genetic diseases. Intronn brings advanced pre-clinical programmes in haemophilia and dyslipidemia that integrate extremely well and should significantly accelerate the programmes recently established by VIRxSYS in the same areas and with the ability to use SMaRT™ across a broad range of other disease applications.

VIRxSYS lead application, VRX496 (a CD4 T cell treatment against HIV), successfully completed Phase I trials in November 2006 and has now moved on to Phase II trials. VRX496 continues to be the only lentiviral vector currently administered in human ethical trials approved by the US Food & Drug Administration. Both companies recognise the considerable synergy between the two technologies, with SMaRT™ providing a strong pipeline of RNA products through the VIRxSYS lentiviral vector delivery platform.

By combining the two technologies in an all stock transaction, both companies will participate directly from the considerable upside potential of the combined platforms and remove duplication of costs and effort. Financial terms have not been disclosed.

Proteome Sciences will keep shareholders appraised of significant developments at VIRxSYS, in particular, news relating to the Phase II clinical trials. Further details can be found in the press release at www.virxsys.com.